Fluid stripping devices

ABSTRACT

A wash-draw apparatus is improved by use of a multichanneled stripping guide located in the path of yarn emerging from the liquid bath in the apparatus. The guide extends below the bath surface and includes additional yarn contacting surfaces above the surface of the bath.

Uniiefl States Patent 91 Wilson Oct. 16, 1973 [54] FLUID STRIPPING DEVICES 2,292,629 8/1942 Fumess 68/175 X 3,421, 46 1 969 W'l .l 6 [75] Inventor: Roger Allan Wilson, Waynesboro, 3 H 8/175 Primary ExaminerWilliam 1. Price [73] Assigneez E. l. du Pont de Nemours and A Company, wilmingmn D e]- Attorney1-1oward P. West, Jr.

[22] Filed: Feb. 22, 1972 [21] Appl. No.: 228,167 [57] ABSTRACT I Q A wash-draw apparatus is improved by use of a multi- UuS. u R f [51] ll!- Ci. B05! g g from the bath i the apparatus. The [58] Fleld 0i SGIICI'I 68/175, 181 R guide extends below the bath surface and includes ditional yarn contacting surfaces above the surface of [56] References CIted the bath UNITED STATES PATENTS 2,369,809 2/1945 Spangler 68/175 3 Claims, 4 Drawing Figures Pmzman w lm 3.765.195

' SHEET 10F 2 FIG. 1

. F-L'UID ST'RIPPING DEVICES BACKGROUND OF THE INVENTION Thisinvention is concerned with the liquid treatment I of .movingfilamentary' yarns and morespar'ticularly with meansto improve efficiency of sequential contacts of yarns with a-plurality of liquids by morethorough strip- .ping of a liquid from'the yarnafter immersion therein.

In'the treatment of yarns in a multiplicity of liquid baths as, forexample, in employing means to applya reagent uniformly 'tothe-surface thereof or a meansto extract a solvent therefrom it-is well known'that as the speed of yarn'travel increases so does the rate ofcarryover ofliquid from-one bath to'the next. In US. I-"at.

No. 3,381,506, it isshown that a yarn traveling upwardly from a water bath at about 400 ypm can carry out abouteighttimes its weight of water. Asspeeds increase beyond 400 ypm, the carry-over is much greater. This greatly reduces efficiency ofthe operation. Further additional meansmust be provided to collect carry-over from the final bath in order to avoid a serious housekeeping problem.

With higher speed operations, it is also importantto minimize the number-and severity of contacts between wet yarn and stationary surfaces; the high friction of such contacts can be adverse to mechanical quality of the yarn.

A means involving minimal yarn contact with stationary surfaces, which minimizes liquid carry-over in processes involving treatment of' yarn by immersion in one or more liquids wouldbehighly desirable.

SUMMARY OF THE INVENTION This invention provides novel means "to reduce the quantity of liquid transported out of a bath ofliquidby a moving yarn. It also provides a simple means for reducing the tendencyfor Btu/inning" of adjacentparallel yarns under the influence of a column of liquid lifted from the bath bythe yarn.

These and other advantages are provided by this invention in a process for o'n-the-run sequential contacting of two or more filamentary strands-with liquids in a plurality of'baths comprisingconducting the strands along separate defined .paths into and out of each bath of liquid. The apparatus improvement comprises a multichanneled guide extending below the surface of the bath with each channel being in alignment with a separate defined .path so the yarn passes through the channels as it 'moves in its path of emergence through the bath. The channels are defined by three or more substantially parallel plates, the bottoms of which are at or below the surface of the baths and oriented with their major faces lying in substantially vertical planes which intersect the plane which includes the paths of said strands, the upper surfaces of said plates being above the normal liquid level or submerged no more than one-half inch, said channels having a height of threefourths inch to 1 inch, a width equal to one-eighth to one-sixth of their height, and a length of 2X their height, said strands being positioned within the channels defined by said plates by light contact with yarn contacting surface members holding the plates in spaced relation to each other, said members being located about two-thirds of the distance from the ends of the plate members. The strand after emerging from th bath lightly contacts one or more additional guides be BRIEF DESCRIPTION OF THE DRAWINGS 'FIG. 1 is an over-all schematic cross-sectionalelevation view of a multiple-bathextraction-drawing process representing one embodiment of this invention.

FIGS. 2a and 2b are front and side schematic elevation views respectively of a four-strand liquid stripper such as may be employed in the process of this invention.

FIG. 3 is an enlarged perspective view of a section of stripper'plate members with an associated yarn contacting surface member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIG. 1, filamentary strands 10 from source not shown are conducted over driven rolls "l2 and idler rolls 14 which are submerged in baths of extractionliquor '16. Fresh extraction liquor is supplied to the fin'al bath through inlet pipe 18, it flows by gravity counter to the direction of strands l0 and is removed atoutletpipe 19 for redovery of the solvent it contains. The surface speeds of driven rolls 12 increase from strand entrance to exit according to a pattern selected to provide the desired extent of drawing. Thus, the strand emerging from the final bath travels at a speed several times as fast as it does on entering the firsttank.

The paths of the strands as they leave the submerged,

idler rolls are diverted slightly by a liquid stripper generally designated 20 which is positioned near the surface of the liquid in each bath. Guide 20 includes a multichanneled stripper portion 22 and a ladder portion 24 connected by side members 26.

The multic'hanneled portion 22 shown in the drawings comprises five plates 23 in a substantially equispaced parallel relationship with their major faces 230 being in substantially vertical planes that intersect the plane that-includes the vertical strand paths. The plates 23 are held-in spaced relationship to each other by the yarn contacting surface members 25a formed on guide bar 25. The ladder portion 24 includes horizontally orisurface of the liquid. Multichanneled guides 22 have been found to operate successfully with channels having a height -H of three-fourths inch to 1 inch, a width equal to one-eighth to one-sixth of their height H, and a length L that is twice their height H (FIGS. 2-3). Multichanneled stripper portion 22 is fixed in an attitude, relative to the strand path, which permits a light contact between surfaces 25a and the strands, one strand being positioned in each channel defined by a pair of adjacent plates 23.

Such liquid strippers as are provided in this invention provide several advantages over devices known in the art. They allow close positioning of individual ends and higher speed of yarn travel, thus increasing substantially the productivity of the liquid-contacting operation. It has been found that a spacing of as little as onefourth inch between filamentary strands can be employed without webbing of transported liquid into a continuous sheet. If webbing occurs, as will happen at a spacing of one-half inch or less in the absence of the stripper, carry-over can be as high as lOO parts by weight of water per part of yarn. At a spacing of onefourth inch, using the apparatus and process of this invention, carry-over of water is typically reduced to 2 pounds water per pound of yarn with the attendant improvement in efficiency of strand-liquid contacting.

A second major advantage in the apparatus and process of this invention is in essentially complete absence of twinning." When water webs between two running filamentary strands as they emerge from the bath, the two strands frequently are brought together or twin. Sufficient turbulence frequently is present in the web to intertwine the filaments of two or more strands into a single bundle which will not always separate on-therun into the original strands at the next guide. Broken filaments and discontinuities thus are the result of twinning. Thus a substantial advantage of the apparatus and process of this invention is seen in improved quality of the yarn, better continuity of the process and, thereby, an over-all improvement in the economies of the operanon.

What is claimed is:

1. In an apparatus for contacting a plurality of strands of yarn with a liquid wherein the strands are moved upwardly and downwardly in separate substantially vertical paths through a liquid bath, the improvement comprising: a multichanneled guide extending below the surface of said bath with each channel of said guide being in alignment with a separate path, said yarn passing through said channels as it moves upwardly, said channeled guide comprising three or more equispaced parallel plates having major faces lying in substantially vertical planes that intersect the plane that includes the vertical yarn paths, said plates being held in said spaced relationship by a plurality of substantially horizontally oriented yarn contacting surface members, said members being below the surface of said bath.

2. The apparatus as defined in claim 1, including a plurality of substantially horizontally oriented bars mounted-across the upwardly moving yarn paths.

3. The apparatus as defined in claim 1, said channels having a width of from one-eighth to one-sixth of their height and a length of about twice their height. 

1. In an apparatus for contacting a plurality of strands of yarn with a liquid wherein the strands are moved upwardly and downwardly in separate substantially vertical paths through a liquid bath, the improvement comprising: a multichanneled guide extending below the surface of said bath with each channel of said guide being in alignment with a separate path, said yarn passing through said channels as it moves upwardly, said channeled guide comprising three or more equispaced parallel plates having major faces lying in substantially vertical planes that intersect the plane that includes the vertical yarn paths, said plates being held in said spaced relationship by a plurality of substantially horizontally oriented yarn contacting surface members, said members being below the surface of said bath.
 2. The apparatus as defined in claim 1, including a plurality of substantially horizontally oriented bars mounted across the upwardly moving yarn paths.
 3. The apparatus as defined in claim 1, said channels having a width of from one-eighth to one-sixth of their height and a length of about twice their height. 